identification of two species Essay

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Volume 10

Article 8


Identification of Two Unknown Species of Bacteria

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Albrecht: Identification of Two Unknown Species of Bacteria

Identification of Two Unknown Species of Bacteria by Anna Albrecht
(Microbiology 1420)

Introduction axonomy is defined as ―the science that studies organisms in order to arrange them into groups (taxa)‖ (Nester, 2012). This seemingly simple description belies both the task of arrangement and the centuries of work that laid the foundation of the science. The science of taxonomy has grown from an artificial, imposed system of categorization based on gross physical characteristics to a highly sophisticated study of genetic evolution.
Carl von Linne, an 18th century Swedish physician, is considered by many to be the father of modern taxonomy (National Agricultural Library, n.d.). Linne is credited with developing an orderly system for naming and classifying plants based on reproductive structures, eventually publishing this work in Species plantarum (1753). His method of binomial nomenclature, using the genus and species as the scientific name of a particular organism, is still in use today.
Advances in Microbiology and Molecular Biology bring ever-increasing detail to the classification of microbial life. Gene mapping shows similarities between species at a molecular level, perhaps giving insight as to the evolutionary path of an organism. Carl Woese, a molecular biologist at the University of Illinois at Urbana, created controversy in the biology community when he announced his discovery that there exists a category of single-celled organisms distinct from prokaryotic and eukaryotic cell structure (Page, 1998). Woese argued that the then-contemporary method of classification, based on phenotype or even cellular structure, misses the most compelling information about organisms. By comparing the nucleic acid sequences of similar microorganisms, scientists can more accurately discern relatedness. He proposed the creation of a third taxon, called a
Domain. He proposed the Domain Archaea as the third evolutionary lineage. (Woese, 1990)
Scientists now routinely use genetic sequencing to identify microbes, however, it is costprohibitive for most university microbiology labs to own such equipment. Microbiology students rely on observation of colony morphology, including size, shape, color and texture, to begin the process of identifying a microorganism. Microscopic examination, particularly after Gram stain or acid-fast stain reveals cell shape, size and staining characteristics. Biochemical testing, such as aerotolerance, further differentiates microbes based on optimal growth requirements. Other tests, including urea or gelatin hydrolysis measure the metabolic capabilities of an organism. Still others, such as nitrate reduction, test for the presence of end products to determine enzymatic pathways used by a microbe
(Nester, 2012). By careful analysis of the requirements for cellular growth and metabolism, a microbe can be identified.
The purpose of the unknown lab is to apply the systematic reasoning learned in class to identify the prokaryotic bacteria in two unknown samples.


The tests performed throughout the process of identifying unknown samples 16 A and 16 B were followed exactly as specified in the text Microbiology: Laboratory Theory & Application
(Leboffe, 2008).

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